Any discussion of the possible change in the union system should begin with the Taft Hartley Act of 1947. It was that bill that fundamentally changed and weakened the power of labor unions from the original Wagner Act of the 1930's.
Wikipedia has a pretty good article on the subject. Here is a very small part
The Labor–Management Relations Act, informally the Taft–Hartley Act, is a United States federal law greatly restricting the activities and power of labor unions. The Act, still effective, was sponsored by Senator Robert Taft and Representative Fred A. Hartley, Jr. and legislated by over-riding U.S. President Harry S. Truman's veto on June 23, 1947; labor leaders called it the "slave-labor bill"[1] while President Truman argued it would "conflict with important principles of our democratic society"[
One of the real controversies of Taft Hartley was that it was promoted by business leaders and politicians who wanted to quell or stifle the great outbreak of labor unrest that occured after World War II.
Millions of GI's fought fascism overseas and defeated it. They defeated a system where the power of government was combined with the power of corporations to stifle the common man and take away his rights. They returned home in 45 and 46 and wanted to exercise the rights that they had fought so hard for in the service. They had beat fascism overseas but were now faced with powerful corporate interests here in America.
The lobbied and struck for better wages as was their right under the National Labor Relations laws. Two main groups of congressman combined to pass Taft Hartley. The first was anti-union Republicans who were against unionism as a matter of philosophy and principle. The second was Democrats, primarily from Southern States with strong laws to stop or stifle unions. These two groups formed a temporary alliance to pass Taft-Hartley in 1947.
As you can see by the above comments, it was called a "slave labor bill" and the President himself said it conflicted with basic democratic rights. Truman vetoed the bill but the coalation in Congress held and they overrode that veto and it became law.
It is that law, and subsequent amendments and court rulings based on that law, which gives us the current system of union elections in the workplace.
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